the name and VI delimiter can be omitted from an attribute specification only if SHORTTAG YES is specified

Cause:

means that the name of an attribute and the equal sign cannot be omitted when specifying an attribute. A common cause for this error message is the use of "Attribute Minimization" in document types where it is not allowed,

Example:

textexample textexample

Bad:
textexample
textexample
Good:
textexample textexample

Solution:

textexample textexample

References: